22-EPN3-088: Scrutinising bio- and geo-signatures in support of the Raman interpretation of space missions data
Visit by Ana de Dios Cubillas, CSIC-INTA (Spain) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit:17 – 28 April 2023
Report Summary: This project is devoted to investigate geo- and biosignatures that can be preserved in mineral assemblages formed in extreme aqueous terrestrial environments. Environments such as subaerial hot springs that could had existed on early Mars, and cold-seep marine environments that can develop in icy-moon oceans are particularly interesting for astrobiology. In order to achieve this goal, we use information obtained by Raman spectroscopy and SEM/EDX microscopy.
Raman spectroscopy is a recently incorporated analytical technique in the payload of several space missions: SHERLOC@Perseverance, Supercam@Perseverance, RLS@ExoMars and RAX@MMX. It is based on the scattering effect generated by the interaction of photons with the electron density of the chemical bond of a molecule. The position and width of the Raman bands give information on the structure, chemical and isotopic composition and crystallinity of mineral. Studying changes in Raman frequencies allows to evaluate the biological or inorganic origin of the sample. This methodology is relevant for the in-situ identification of geo- and bio-signatures in soil/rock samples collected during space missions.
Several bio-mediated minerals sampled from several hydrothermal and cold-seep areas were characterised by micro-Raman spectroscopy coupled with scanning electron microscopy (SEM/EDX). Obtained Raman spectrum was correlated with its texture in order to identify patterns that would allow us to assess the biological or inorganic origin. We observed Raman band shifting and width changes. These results should be complemented by further experimental work to determine the involvement of bio-mediation processes.
Read the full scientific report, with kind permission by Ana de Dios Cubillas.
21-EPN-FT1-016: Metabolic responses of Antarctic melanised microorganism to simulated Martian conditions
Visit by Ilaria Catanzaro, University of Tuscia (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 30 May – 03 June 2022
Report Summary: Current hostile conditions on the surface of Mars entail that, if any life form has ever existed on the planet, it may have adopted survival strategies like those evolved by terrestrial microorganisms inhabiting extreme environments e.g. Antarctica. There, one of the most common strategies observed is the cryptoendolithic microbial growth where free-living black fungi living along with algae and lichens within rocky interstices serve as a shield from excessive harmful solar radiation, and their extremotolerance can be mainly due to the presence of thick, highly melanised cell walls.
The ability of these cryptoendolytic microorganisms to thrive under extreme conditions raises the question of whether they cope with them by also regulating their metabolic expression in addition to melanin production, and whether a hypothetical microbial life on Mars could ever have arisen with similar adaptive strategies. In this optic, this study aimed to examin the metabolic regulation of melanised, cryptoendolithic microorganisms in martian scenario. To achieve this goal, colonies of the cryptoendolithic black fungus Cryomyces antarcticus previously exposed to simulated martian conditions such as perchlorates, sulfatic regolith soil and γ radiation, were then analysed with NMR spectrometry at the Center for Microbial Life Detection of the Medical University of Graz. Sample preparation and analysis were carried out in the Facility using standard protocols. Although only preliminary data are available at the time of report writing, significant differences in fungal metabolic expression were observed between the different simulated martian conditions tested.
20-EPN2-078: Metagenomic analysis of the outstanding moonmilk speleothems from Grotta Nera, Majella National Park
Visit by Martina Cappelletti, University of Bologna (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 4-7 October 2021, 26 April 2022 (virtual visit)
Report Summary: This project focused on the analysis of three samples from the Black cave (Grotta Nera) located in Majella Park (Abruzzi region, Italy). This cave presents outstanding calcitic moonmilk structures that are unique in the World in terms of both abundance and dimension.
Metagenomic and metabolomic analyses of three samples (A1, apical; A2, lateral; A3, core) collected from one of the moonmilk speleothem from Grotta Nera, were performed. The DNA was extracted using the DNA powersoil kit (Qiagen) modified to include a bead-beating step with MagNA lyser (Roche) for the initial sample treatment. MG-RAST was used to analyse the metagenomic data considering both the taxonomy composition and the functional categories (KO categories). The taxonomy composition of the metagenomic sequences indicated that the dominant phyla were Proteobacteria, Actinobacteria, Firmicutes, Planctomycetes, Acidobacteria, and Verrucomicrobia. Actinobacteria were more abundant in the A1 and A2 as compared to the A3 sample, while in A3 Proteobacteria (in particular, Betaproteobacteria) was enriched as compared to other two samples. The metabolomic analysis was carried out using NMR, extracting the metabolites from 100 mg of each sample (in triplicate). The results indicated that in A2 and A3 samples were enriched by specific metabolites (glycerol in A3 and alanine, acetate, ethanolamine and 3-hydroxybutirate are enriched in A2) suggesting distinct metabolic activities in the microbial communities of these two samples.
Read the full scientific report, with kind permission from Martina Cappelletti.
20-EPN2-035: Characterisation of the composition and metabolic profiles of microbial communities in Antarctic dry soils as a model for Mars explorations
Visit by Fabiana Canini, University of Tuscia (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 4-8 October 2021
Report Summary: McMurdo Dry Valleys (MDVs) of Antarctica, the coldest and driest desert on Earth, characterised by strong UV irradiation and strong winds, are considered one of the closest terrestrial analogue of the Martian environment. Only microbial life-forms inhabiting the rocks and soils can survive in these harsh conditions. Endolithic communities have been thought to be the predominant life forms and have been widely characterised, while the drivers of microbial colonisation in MDVs dry permafrost are still barely known. It is still not clear if life forms found in soils through molecular approaches are metabolically active or present as dormant wind-transported spores, propagules or death cells.
Additionally, the possible contribution of the endolithic communities to soils diversity has never been investigate in MDVs. As the endolithic growth has been hypothesised as one of the adaptive
strategies of putative Martian microbial life-forms, the hypothesis of rock fragments dispersal should be investigated, to give new perspectives on life-traces search on Mars.
The microbial diversity and metabolic activity have been characterised in soils collected in MDVs at increasing distance from a colonised sandstone outcrop and in the corresponding rocks samples. The microbial composition and functionality have been investigated through shotgun metagenomics, while the metabolomics profiles have been defined through NMR metabolomics. This description may give unprecedented information on whether the cells found are active or not and on how they metabolically adapt and thrive in this environment. The results may be useful in the frame of search for chemical biosignatures within future Mars explorative missions.
Read the full scientific report with kind permission of Fabiana Canini.
20-EPN-083: Beyond Antarctica: a survey on detection of life in endolithic fossils supporting future space exploration missions
Visit by Federico Biagioli, University of Tuscia (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 14-20 November 2021 (in person visit), 21-26 April 2022 (remote analysis)
Report Summary: Endolithic growth is the ultimate microbial adaptation and the predominant life-form in the far extreme ice-free areas of Antarctic deserts, considered among of the best analogues of the Martian environment on Earth. Although recent molecular studies have started to shed light on the biodiversity, distribution and composition of crypto-endolithic communities in visibly colonized rock samples, fossilized or apparently not colonized endolithic communities remain largely unexplored. Amplicon-sequencing analysis of fungal and prokaryotic domains on both not colonized and fossil samples were here performed to gain information about preservation of extinct life traces within rock and evidences of possible life detection also in eventual extra-terrestrial samples. Genomic DNA was extracted and sequenced from 24 fossil and 6 apparently not colonized rocky samples, resulting in a high number of reads and mapped ASVs for fungal (657,626 quality- filtered reads and 161 ASVs), bacterial 16S rDNA (1,296,594 reads mapped into 839 ASVs) and 16S archaeal specific (2,813,402 validated clustered in 3,514 ASVs) datasets. The high number of reads and ASVs achieved allows us to suppose that rocks not only represent a perfect refuge from harsh external environmental conditions, but also an important preservation ark for biosignatures of past life forms.
Read the full scientific report with kind permission of Federico Biagioli